The Mutant and Transgenic Rodent Core (MTRC) is directed by Maria Moalli. The major purpose of MTRC, is to provide Nathan Shock Center (NSC) scientists with aged mice of genotypes that provide otherwise unavailable opportunities to investigate the basic biology of aging or the pathophysiology of age-related disease states. A facility such as the MTRC operated by the NSC at the UM does not exist anywhere else in the country. The NSC's MTRC is specifically dedicated to exploiting for gerontological research the wide range of mutant and transgenic currently available, but not yet studied in the context of aging. The MTRC functions as a service core with the following specific aims: (1) the support of the per diem costs of aging a wide variety of mutant/transgenic rodents, (2) the provision of gross necropsies and histopathologic data on age-related lesions for specific genotypes of mice, (3) the maintenance of select colonies of mutant/transgenic aging mice for NSC scientists, and (4) the development of new models based on transgenic, mutant, or knockout mice. Over the four years of support, the MTRC has supported eleven projects with five faculty sponsors. Most projects were funded for two years, which was the usual time required to obtain mice at the ages required for the study. The projects funded during the current grant period included: the aging of mdx and transgenic-mdx mice, the relationship of early growth rate and longevity, the longevity of dwarf mice, the role of the androgen receptor in breast cancer, a comparison of wild and laboratory inbred mice, the aging of factor IX transgenic mice, studies of rhodopsin transgenic and knockout, DNA methyltransferase knockout, and IL-6 knockout mice, estrogen receptors, and a genetically heterogeneous strain the UM-HET3 mice. In conjunction with the MTRC, the UM Transgenic Animal Core (directed by Sally Camper) has generated a number of novel transgenic-mdx lines that have been used extensively by Chamberlain and his colleagues locally and in six other laboratories world-wide. The MTRC supported projects have led to twelve publications, six grant applications to NIH, with two funded and one pending R0-1 grants, and two funded and one pending P0-1 grants. The MTRC has had a significant impact on the use of transgenic mice and of naturally occurring and engineered mutant mice both among NSC scientists on the UM campus and among their colleagues in the USA and at foreign institutions.